(a) Field of the Invention
The present invention relates to a new design for the structure of a clutch device for a transmission wheel and transmission shaft. Two brake rings surround a hub axle contained in a brake hub. By utilizing the braking time differential of the two brake rings, one of the brake rings can force a loose pin to part from the transmission wheel so that idling, from the separation of the transmission wheel and transmission shaft, is achieved.
(b) Description of the Prior Art
There are many known clutch devices for transmission wheels and transmission shafts. To the common machine tools frequently seen, a clutch braking action is particularly important. It is particularly important in the operation of a punch press by a cam mechanism by a transmission wheel and a transmission shaft. In the punching process, it is necessary to start braking at the point of maximum elevation, and there is no way to brake instantly at any angle within a 360.degree. range. In the event that a breakdown of the machine elements of the braking unit occurs, such as the break of a cotter, the drop of a pedal spring, etc., the punch press will fall off and cause an accident. If unable to brake in an emergency, there are often caused personal injuries (like broken fingers, etc.). At the present stage, although there are air compressors ready for control, the equipment costs are too high, and factories under scale cannot bear such an expense. Besides, if a safety valve does not work, an explosion might happen, similar to placing a bomb nearby, making workers uneasy. Aside from this, some electronic control mechanisms can be used for safety purposes, but these are not ideal, due to similar reasons of high cost and inconvenient maintenance.